Fragments of cards marked with iodine-125 were found during an inspection at a waste treatment plant.
Photograph: Alamy Stock Photo

A German restaurant owner is in hot water for allegedly marking playing cards with a radioactive substance to rig games.

Berlin police said on Tuesday the 41-year-old woman had daubed iodine-125 on specific cards, which allowed them to be identified by a gambler with a concealed detector.

Police launched an investigation after radioactive card fragments were found during a routine inspection of a garbage truck at a waste treatment plant a year ago. Investigators then followed the vehicle’s route to determine the origin.

They raided the woman’s restaurant and other premises earlier this month and found 13 radioactive card pieces.

Iodine-125 is commonly used for medical purposes and only poses a health risk through direct contact with no protective clothing.